The basic function of black-out curtains is to prevent any and all light from entering the room. They can also be reference by different names such as brightness diffuser, light screens and others.
Velvet black-out curtains are going to use an extra thick lining to add extra protection from light shining through. The thicker the lining and materail the darker your room will be.
Black-out curtains are used for different reasons such as people who have night jobs, need to sleep in without disruption, or watching movies or playing games.
The easiest way is typically to use curtains because they will usually be cheaper and more readily available than other types of black-out window treatments. The thicker the curtain material, the better effectiveness they will have.
That is what makes velvet curtains perfect for this because of the thick durable fabric that is used to create velvet. They also give a stylish feel and if you are using the curtains to black out the room for any sort of media purpose, such as movie watching, then the velvet curtains really fit the motif of a movie theater.
Black Out Velvet Curtains
Some people will combine multiple methods with the velvet curtains for blacking out their room. One reason it works well to combine different source is because althought black-out velvet curtains can do a great job, because of the nature of curtains they do not typically lie flat on the wall so normally there will be small openings through-out the blinds, but if you also combine it with shades or blinds for black out purposes then the thickness of the velvet will block out most of the light, where the blinds or shades will get the nooks and crannies that might have been missed by the velvet curtains.
One advantage to shades and blinds combined with curtains is that you can pull the curtains away when and if you do want light in the room on some occasions and then just flip the blinds or pull up the shades and the light will shine on in.